1D model simulations suggest biofilms can suppress cathodic H2 bubble formation
Microbial electrosynthesis (MES) electrochemically generates H2 for the reduction of CO2 into acetate by acetogens. So far, the importance of a biofilm on the cathode of such systems remains under debate. Here, we investigated the role of cathodic biofilms through computational modelling. We developed MES-BIOFILM, a comprehensive one-dimensional model to simulate steady-state H2 and CO2…
Microbial electrosynthesis (MES) generates hydrogen for reducing carbon dioxide into acetate. However, the impact of biofilms on MES cathodes remains unclear. Researchers employed computational modelling to explore the role of cathodic biofilms. They created the MES-BIOFILM model to simulate H2 and CO2 gradients within cathodic biofilms, taking into account limited hydrogen solubility.
The study analyzed biofilm properties, such as thickness, cell density, and hydrogen consumption rate. The results showed that cathodic biofilms help reduce H2 loss by consuming H2 within the biofilm and prevent H2 bubble formation by keeping surface H2 concentrations below saturation levels. The model predicts that biofilms with high cell density and high H2 consumption rate can increase the current density threshold for H2 bubble formation by up to fivefold compared to bare electrodes.
However, biofilms need to be at least 50 millimeters thick to achieve this effect, while CO2 diffusion limitations occur above 200 millimeters. The findings emphasize the importance of biofilms in enhancing MES performance, but further experimental validation is needed.
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